Interruption of direct currents (DC) is one of the major challenges for the realization of multi-terminal DC networks (MTDC). Several approaches have been investigated. For such a system, speed is an important requirement, and very high speeds can be achieved using a semiconductor-based circuit breaker.
Semiconductor-based circuit breakers described, for example, in U.S. Pat. No. 5,999,388 and EP 0 867 998, generally include a semiconductor switching assembly having a plurality of semiconductor switches in series. A plurality of arresters is arranged in parallel to the semiconductor switches and is used to limit the voltage over each switch.
One drawback of this type of arrangement is the fact that, when the switches are switched off, a residual current continues to flow. This current primarily flows through the arresters and, to a smaller extent, through the semiconductor switches.